The invention pertains to a device for the 3D free-form bending of profiles with constant outside dimensions over their length, particularly with a circular shape, wherein said device comprises a feed unit that contains a rotary drive for turning the profile about its longitudinal axis and serves for moving the profile with a longitudinal axis in a feed direction that extends parallel to this longitudinal axis, namely through a guide element with a through-opening that adjoins the surface of the profile and a bending sleeve that at least partially encloses the profile to be bent and is arranged downstream of the guide element referred to the feed direction, wherein said bending sleeve is held in a carrier element and can be pivoted about an axis that extends perpendicular to the feed direction of the profile, as well as displaced perpendicular to the longitudinal axis and the pivoting axis, together with said carrier element such that the bending sleeve acts upon the profile in a bending fashion.
3D free-form bending devices are known from the state of the art. For example, JP 08 257 643 A discloses a 3D profile bending device, in which a profile is moved through a stationary guide element and a bending sleeve that is arranged downstream of the guide element referred to the feed direction and integrated into a carrier element. The carrier element is held in a receptacle frame such that it can be turned about a first axis that extends through the center of the bending sleeve perpendicular to the longitudinal axis of the profile to be bent. The receptacle frame itself is supported such that it can be turned about a second axis of rotation that extends through the center of the bending sleeve, namely perpendicular to the profile axis as well as perpendicular to the first axis. In addition, the receptacle frame can be displaced along both axes. The profile can be bent three-dimensionally by respectively adapting the rotational movement and the displacement of the receptacle frame relative to the rotational movement of the carrier element in the receptacle frame accordingly.
The disadvantage of this bending device is that the different rotational and translational movements of the carrier element and the receptacle frame need to be exactly adapted to one another in order to bend the profile into the desired shape. This not only requires high investment costs, but also a complicated CNC control of the bending device.
EP 0 928 646 A1 discloses another bending device that operates in accordance with the same principle as the above-described device. In addition to the rotational movement about and the translational movement along the respective axes that extend perpendicular to the profile axis and lie orthogonal to one another, the carrier element of this device can also be turned about the longitudinal axis of the profile in order to achieve the desired torsion of the profile during the bending process. Although all degrees of freedom of the bending process are realized with this device, a total of five rotary and linear drives is required in addition to the feed unit, wherein said drives also need to be correspondingly adapted to one another. This means that the drives need to fulfill very high requirements with respect to precision and synchronism, and that this bending device cannot be realized in a cost-efficient fashion.
EP 0 928 645 A1 discloses a simplified variation of a bending device for the 3D free-form bending of profiles. Analogous to the above-described state of the art, the feed unit of this device moves the profile through a non-rotatable guide element and a U-shaped, open bending sleeve arranged downstream thereof. The guide element is inserted into a sleeve that is non-rotatably connected to the machine frame and on which an outer sleeve is rotatably supported. In this case, the axis of rotation of the outer sleeve coincides with the longitudinal axis of the profile. The outer sleeve contains a boom that extends in the feed direction and on the end of which a support element carrying the bending sleeve is arranged such that it can be turned about an axis that extends perpendicular to the feed direction and is laterally offset relative thereto. The position of this axis relative to the bending sleeve is chosen such that the rotational and translational movements of the bending sleeve required for adjusting the desired bending radius can be achieved by means of a single pivoting movement. The three-dimensional bending of the profile is realized by turning the outer sleeve and the open bending sleeve connected thereto about the profile axis by means of the support element and the boom, namely by a certain angle that corresponds to the desired change in the position of the bending plane. Subsequently, the desired bending radius is adjusted once again by turning the bending sleeve accordingly, and the bending process is continued in a new bending plane.
In comparison with the other bending devices described above, this device has a much simpler design that only requires two drives in addition to the feed unit. However, one disadvantage can be seen in the complicated mechanism for turning the bending sleeve by means of the rotatably supported outer sleeve. This makes it impossible to realize this device in a compact fashion. In addition, a frequently undesirable and extensive straight transition section is frequently formed during the phase, in which the device is adjusted from one bending plane to another bending plane. This device is only suitable for profiles that have a circular cross section, namely because the profile needs to be held in the bending sleeve such that it can be axially turned.
Another 3D bending device for bending profiles with a circular cross-sectional shape is known from practical applications, wherein the profile is moved through a non-rotatable guide sleeve that encloses the profile with a positive fit, as well as through a bending sleeve arranged downstream thereof, wherein said bending sleeve is held in a carrier element and also encloses the profile with a positive fit. The rotational and translational movements of the bending sleeve required for adjusting the desired bending radius can be realized due to the fact that the bending sleeve is held in a rocker by the carrier element such that it can be turned perpendicular to the feed direction. In this case, an actuating cylinder is used for turning the bending sleeve by means of a boom. In contrast to the previously described state of the art, the bending plane is not changed by turning the bending sleeve about the longitudinal axis of the profile in this case, but rather by turning the bending sleeve about its longitudinal axis with the aid of a drive integrated into the feed unit. This results in the relative movement between the bending sleeve and the profile to be bent taking place in an unchanged fashion.
These measures make it possible to achieve a more compact design of the bending device than in the previously cited state of the art. Nevertheless, this device is also unsuitable for bending profiles with non-circular cross sections because it must be possible to turn the profile in the guide sleeve as well as in the bending sleeve.
The relevant state of the art also discloses drawing/bending machines for hollow profiles that have become quite popular in the automobile industry. However, these machines are only able to bend profiles in one plane, i.e., 2-dimensionally. A drawing/bending machine for thin-walled metal pipes is described in DE 100 20 727 C1. In this case, the front end of the pipe is clamped in position in a fastening device by means of clamping jaws. When processing thin-walled pipes, the inside of the pipe needs to be supported by a grip head in the clamping region and by a bending block in the bending region. Once the pipe is fastened in the desired position, the bending process is initiated by turning a bending table with a circular shape that defines the attainable bending radius about its axis of rotation. This causes the pipe to be drawn forward and to be simultaneously bent by the bending table. In addition to being limited to bending processes in only one plane, the fundamental disadvantage of such drawing/bending machines can be seen in the fact that no variable radii and no bending about the longitudinal axis of the profile can be realized.